1. Field of the Invention
This invention relates to power transmission equipment and, more specifically, to circuit breaking equipment for D-C power transmission systems.
2. Prior Art
In recent years the electrical power industry has shown a significant trend towards shifting from A-C power transmission to D-C power transmission. Such D-C power transmission is done at very high voltage to assure high transmission efficiency. With higher transmission voltages come greater problems of leakage to ground and their associated hazards. In A-C power transmission systems such leakage currents are detected by a zero-phase current transformer, the output of which causes a tripping device to open the contacts of the breaker. Such a circuit obviously will not suffice in a D-C power transmission system. D-C leakage current detection and circuit breaking systems have thus far been unavailable.
It is an object of this invention, therefore, to overcome the general disadvantages set forth hereinbefore.
It is a further object of this invention to provide a leakage current detection and circuit breaking system for protection of D-C power transmission line systems.